The current French administrative practice regarding passports does not make it mandatory for a foreign minor (under 18 years old) to travel with an individual passport if he/she has been entered in to one of his/her parent's passport.

Neither does it make mandatory that a picture of the minor should appear in his/her parent's passport.

No specific document is required by France when a minor is traveling with his/her own passport, whether alone or accompanied by an adult.

However, when a child is traveling alone, he/she cannot travel with his parents passport even if he/she has been registered on it. An individual passport is then mandatory.
The consulate also advises the minor to take with him/her a written parental consent for the specific trip with a photocopy of the parents' identification cards ( driver's licence, passport, or citizenship ).